Principles and problems of assessing the results of medical treatment.

The integration of clinical expertise with the best available evidence from systematic research is the foundation of evidence-based medicine (EBM). The results from a well-designed randomised controlled trial (RCT) is regarded as the best evidence on which to base treatment. In neurosurgical practice fewer treatments are based on the results of RCTs than in medical practice. The reasons are historical, ethical, practical and can be compounded by the surgical learning curve. In neurosurgical practice treatment protocols and surgical indications vary widely. In addition there is a lack of patient orientated, disease specific and generic outcome measures. However, it is a neurosurgical responsibility to provide hierarchical evidence upon which treatment can be based. Comparative audit may offer a solution provided there is high quality data collection, relevant measures of outcome, a defined case-mix and a representative population. Comparative audit can produce bias but neurosurgeons will need to meet the challenge of EBM. Their patients will expect it.